Etching solution application device for offset printing machines

ABSTRACT

An etching solution application device comprising an etching solution application roller for applying an ink-repellent etching solution to a master plate mounted on a master cylinder of an offset printing machine which device operates such that an etching solution can be supplied to the etching solution application roller before it presses against a master plate on a master cylinder. The device also operates such that the etching solution application roller is rendered inoperative during steps other than the etching step in which the etching solution application roller presses against the master plate on the master cylinder to apply the etching solution to the master plate and the master plate discharge step in which the master plate on the master cylinder is removed and discharged from the master cylinder, or during the inking step and duplication step.

U-mted States Patent 1 1 1111 3,731,624 Kaneko et al. 1 May 8, 1973 [54] ETCHING SOLUTION APPLICATION 3,233,538 2/1966 Ritzerfeld etal. ..1o1 14s DEVICE FOR OFFSET PRINTING 3,521,560 7/1970 Schmidlin et a1 ..101 I 148 H H m I FOREIGN PATENTS OR APPLICATIONS [75] Inventors: K311131611, IQtsumi Mizuno,

both ky J p 757,020 9/1956 Great Bntam ..l0l 144 2 a Primary Examiner-J. Reed Fisher [73] Asslgneet Rlcoh C0.,Ltd.,T0kyO,J8P Attorney-Henry T. Burke, Robert Scobey, Robert S. v Dunharn, P. E. Henninger, Lester W. Clark, Gerald [22]; Filed: Sept. 10, 1970 W. Griffin, Thomas F. Moran, R. Bradlee Boal and [21] App. No: 71,172 Chrlstopher C. Dunham 57 ABSTRACT I [30] Foreign Appncauon Prionty Data An etching solution application device comprising an Sept. '15, 1969 Japan ..44/73074 etching solution application roller for applying an inkrepellent etching solution to a master plate mounted [52] U.S.Cl. ..l01/l42,101l148,101/352, on a master cylinder of an offset printing machine 101/425 which device operates such that an etching solution f 5l] Int. Cl ..B41f 7/32, B411 35/06, 1341125/16 can be supplied to the etching solution application [5 Field of Search 101/136-140141445, r ll r f it pr against a ma r plate n a 101/ 148,349-352,425 master cylinder. The device also operates such that the etching solution application roller is rendered in- 6] References Cited operative during steps otherthan the etching step in which the etching solution application roller presses UNITED STATES PATENTS against the master plate on the master cylinder to 3,056,346 10/1962 Gammeter et a1 ..1o1 144 PP Y etchinS Plate and the 3,303,778 2/1967 Tonkin etal. ..1o1/144 master P t discharge p in which the master Plate 3;60,1 0,45 8/1971 Schinke ..101/148 on the master cylinder is removed and discharged 3,577,916 5/1971 Tonkin ..101/148 from the master cylinder, or during the inking step 3,276,363 10/1966 Kuchenpeck et al ..101/349 and duplication step. 3,507,215 4/1970 Schuhmanii ....101/l48 3,463,082 Kaufer 101/ 144 8 Claims, 25 Drawing Figures ZZZ PATENTED" W975 sum m or 10 FIG.

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ETCHING SOLUTION APPLICATION DEVICE FOR OFFSET PRINTING MACHINES BACKGROUND OF THE INVENTION This invention relates to etching solution application devices for offset printing machines. More particularly, the invention is concerned with an improved etching solution application device of the type described.

It is known that, when printing is performed by means of an offset printing machine, an ink-repellent etching solution should be applied to a master plate on a master cylinder before the master plate is inked.

In one method known in the art, means for applying an etching solution to the master plate on the master cylinder includes cotton, cloth or other hygroscopic material which is impregnated with an etching solution and rubbed manually against the master plate. An automated etching solution application device includes a polygonal post of a hygroscopic material which'is impregnated with an etching solution and pressed at one side against a master plate mounted on a master cylinder.

Manual application of the etching solution cannot be adopted in an automated offset printing machine. The use of a polygonal post pressed against the master plate has a disadvantage in that, since the polygonal post cannot be rotated, only one side thereof is brought into contact with the master plate at all times and consequently liable to be damaged. The use of only one side of the polygonal post has deleterious effect on the master plate.

Accordingly, an object of the present invention is to provide an improved etching solution application device of the type which comprises an etching solution application roller adapted to be impregnated with an etching solution and caused to press against a master plate on a master cylinder so as to thereby apply the etching solution to the master plate, such device being characterized in that, when a series of master plates are automatically mounted on and removed from the master cylinder successivly for duplication, a supply of etching solution can be delivered beforehand while the next succeeding master plate is mounted on the master cylinder following the removal of the preceding master plate, so that the etching solution application roller is supplied with the etching solution in an amount sufficient to etch the master plate satisfactorily when brought into pressing engagement therewith. This permits to carry out the etching solution application satisfactorily without damaging the master plate.

Another object of the invention is to provide an etching solution application device which operates such that the etching solution application roller is rendered inoperative during the steps other than the master plate feed step (including the etching step) and master plate discharge step or during the inking step and duplication step so as to prevent the scattering of the etching solution by the rotating roller.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a rotary offset printing machine comprising one embodiment of this invention;

FIG. 2 is a sectional view taken along the line llll of FIG. 1;

FIG. 3 is a view similar to FIG. 2 but showing only the automatic-non-automatic switching actuating member as it is disposed in its lower position in a printing step switching member; I

FIG. 4 is a perspective view of the device shown in FIG. 2;

FIGS. 5 to 7 are sectional views along the line VV of FIG. 2, FIG. 5 showing the printing step switching member in its neutral position, FIG. 6 showing the printing step switching member in its master plate feed position and FIG. 7 showing the printing step switching member in its master plate discharge position;

FIG. 8 is a front view of one embodiment of the automatic master plate discharge command cam;

FIG. 9 is a front view of one embodiment of the automatic master plate feed command cam;

FIG 10 is a side view of an automatic master plate feed and discharge unit comprising an automatic master plate feed mechanism and automatic master plate discharge mechanism;

FIG. 1 I is a fragmentary view of FIG. 10 showing the parts in state in which a command to feed a master plate has been issued;

FIG. 12 shows the parts in a state in which master plate feed mechanism has been rendered operative after a command to feed a master plate has been issued;

FIG. 13 is a side view similar to FIG. 10 but showing the interior of the master plate feed and discharge from which a side plate has been removed;

FIG. 14 is a side view of a master plate grip pawl opening and closing mechanism provided in a master cylinder;

FIG. 15 is a side view of the master cylinder and master plate delivery rollers showing the leading end of a master plate being gripped by the master cylinder;

FIG. 16 is a fragmentary view of FIG. 10 showing the parts in a state after a command to discharge the master plate has been issued;

FIG. 17 is a side view of the master plate discharge mechanism showing the interior of a master plate discharge device by eliminating the side plate of FIG. 10;

FIG. 18 is a side view of an etching command mechanism included in the master plate feed and discharge unit;

FIG. 19 is a side view of an etching solution application device;

FIG. 20 is a sectional view of an immersion roller operating mechanism for the etching solution application device;

FIG. 21 is a side view of an operation control device for the etching solution application device;

FIG. 22 is a fragmentary view of FIG. 21 showing the etching solution application device in an inoperative position as a result of actuation of the operation control device;

FIG. 23 is a side view of an inking device for applying ink to the master plate on the master cylinder;

FIG. 24 is a side view of a cleaning device for cleaning the blanket cylinder; and

FIG. 25 is a side view of the cleaning device showing the device in an operative position.

DESCRIPTION OF THE PREFERRED EMBODIMENT 1. Switching Device, in Association with a Printing Operation Step Switching Member, for Selecting Between Automatic and Non-Automatic Operation In FIG. I, a master cylinder 1, blanket cylinder 2 and impression cylinder 3 are supported by side plates 5 for rotation in respective directions in conjunction with one another. As shown in FIG. 2, a printing operation step switching member 4 is tubular in shape and has a base secured to a bevelled surface 6a formed at the forward end of a tubular shaft 6 which is rotatably mounted on a minor diameter portion 7a of a core shaft 7. Secured to the base of the tubular shaft 6 is a click wave-shaped portion 8a (See FIG. I) in its peripheral edge. A pin 12 attached to a lever lll urged by a spring 9 to move in pivotal motion in an anticlockwise direction about a shaft 10 presses against the'waveshaped portion 8a of the click plate 8 which cooperates with the pin to click stop the step switching member 4 in position A, B, C and D when it is moved from its neutral position N in FIG. 1 to these positions.

Straddling the upper surface of the tubular shaft 6 is a support member (See FIG. 4) which has a U-shaped support 14 secured to its upper surface. An automaticnon-automatic switching member 15 is pivotally supported by a shaft I6 connected to the U-shaped support 14. A forked portion 15a is formed in one arm of the automatic-non-automatic switching member I5 and maintained in engagement with the base of the step switching member 4. A coil spring 17 is mounted over the base portion of the step switching member 4 for maintaining the forked portion 15a of the automaticnon-automatic switching member 15 in an upper posi tion. Thus, the automatic-non-automatic switching member 15 is urged to move in pivotal motion in a clockwise direction about the shaft 16 by the spring 17, as shown in FIG. 2.

A switching actuating member I8 for actuating the member 15 is fitted in the step switching member 4 in such a manner that a head 18a of the member 28 projects upwardly above the upper end of the member Secured to the lower end of the switching actuating member 18 is a pin 19 loosely received in a slot 4a formed in the base portion of the step switching member 4. The forked portion 15a of switching member 15 presses at its upper surface against the pin 19 as the member 15 is urged by the biasing force of the spring 17 to move in pivotal motion in a clockwise direction about the shaft 16. Accordingly, the pin 19 is maintained in engagement with the upper edge of the slot 414, so that the head 18a of the member 18 projects slightly upwardly above the upper end of the member 4 As shown in FIG. 2, a short cylinder 2@ is loosely fitted over the major diameter portion of the core shaft 7. An automatic master plate discharge command cam 21 (See FIG. 8) and automatic master plate feed command cam 22 (See FIG. 9) are rotatably mounted on the short cylinder 20. The other arm ISb of the member 15 extends through a radial slot @a (See FIG. 4) formed in the click plate 8 and has a forward end which is disposed in cam portions 21a and 22a of the cams 2H and 22 respectively. When the member 118 is in its upper position in the member 4 with its head 18a projecting upwardly above the upper end of the member 4 as shown in FIG. 2, the forward end of the other arm of the member 15 is maintained in engagement (See FIG. 5) with arcuate edges 21aI and 22111 (See FIGS. 8 and 9) of the cams 21 and 22 respectively. The cams 21 and 22 have arms 21b and 22b respectively. The cam 21 is urged by a spring 23 mounted on the arm 21b to rotate in a clockwise direction, and the cam 22 is urged by a spring (not shown) mounted on the arm 22b to rotate in an anticlockwise direction. However, the cams 21 and 22 are maintained in their neutral positions shown in FIGS. I and 5 respectively by keeping the arms 21b and 22b in abutting engagement with a stopper 24 attached to one of the side plates 5.

If the switching member 18 is moved to its lower position from its upper position in FIG. 2, then the pin 19 moves downwardly in the slot 4a to move the member 15 in an anticlockwise direction about the shaft 16 as shown in FIG. 3 against the biasing force of the spring 17. Accordingly, the forward end of the other arm 15b of the member 15 moves from its dashand-dot line position ISbA to its solid line position shown in FIG. 3 where it is brought into contact with mountain-shaped edges 21a]! and 2202 (See FIGS. 8 and 9) of the cam portions 21a and 22a of the cams 21 and 22 respectively.

If the member 4 is moved from its neutral position N to its dash-and-dot line position A in FIG. 1 while the member 18 is in its lower position in the member 4, then the member 15 moves in the same direction and the forward end of its arm 15!; comes into engagement with one end of the mountain-shaped edge 22a2 of the automatic master plate feed command cam 22, thereby rotating the cam 22 in the same direction (See FIG. 6). The mountain-shaped edge 21a2 of the cam 21 is slightly displaced from the mountain-shaped edge 22a?. of the cam 22 so that the former cam may not interfere with the movement of the latter cam.

Referring to FIG. 5, a follower arm 25 is pivotally mounted on a shaft 26 secured to a side plate and urged by a spring (not shown) to move in pivotal motion in an anticlockwise direction about the shaft 26. Mounted on a shaft secured to the follower arm 25 is a roller 27 which is maintained in pressing engagement with the crest of a wave-shaped cam portion 220 formed in the cam 22 (See FIG. 9). As the cam 22 rotates in conjunction with the movement of the member 4 to its position A as aforementioned, the roller 27 is brought into engagement with the depression of the wave-shaped portion 22c, so that the follower arm 25 moves in pivotal motion in an anticlockwise direction about the shaft 26 (See FIG. 6).

As shown in FIG. 5, a master plate feed command pin 28 is secured to the free end of the follower arm 25. The pin 28 which extends through an opening 5a formed in one of the side plates 5 and is directed toward the master plate feed mechanism in the interior of the printing machine moves in the opening 5a from a position shown in FIG. 5 to a position shown in FIG. 6 as the follower arm 25 moves in pivotal motion as aforesaid. The pin 23 in this position moves a member connected to a master plate feed device and etching solution application device subsequently to be described and gives instructions to start operating.

If the member 4 is moved from the neutral position N to the dash-and-dot line position A while the member 18 is in its upper position in the member 4, then the forward end of the arm 15b of the member merely moves in sliding motion on the arcuate edges 21a]. and 2211i. of the cams 2i and 22 respectively, so that neither cam 21 nor cam 22 rotates. Accordingly, master plate feed and etching solution application are carried out not automatically but manually by the respective operators.

If the member 4 is moved from its position A to its position B in FIG. 1, the forward end of the arm b of the member 15 moves in sliding motion on the arcuate edges 21a1 and 22a] of the cams 21 and 22 respectively. If the member 18 is in a position shown in FIG. 6 or it is in its lower position in the member 4 which is in its position A shown in F IG. 1, then the forward end of the arm 15b of the member 15 is maintained in engagement with the mountain-shaped edges 21a2 and 22112 of the cams 21 and 22 respectively. Since the cam 21 is locked in position by the stopper 24, the forward end of the arm 15b of the member 15 moves downwardly along the mountain-shaped edges 21a2 and 22a2 when the member 4 is further moved to its position B. Accordingly, the member 18 is restored to its original position.

Thus, when the member 4 is moved from its position A to its position B in FIG. 1, it is not possible to optionally carry out inking of the master plate either automatically or manually and inking is carried out automatically at all times when the member is in its position B. As the member 4 is moved from its position B to its position C, copy sheet feed is carried out automatically while inking is also carried out. The commands to carry out inking and copy sheet feeding are carried into practice by some of the groups of levers and cams shown in FIG. 1. In the copy sheet feeding step, copy sheets 30 resting on a copy sheet feed tray 29, shown in FIG. 1, are fed successively to the impression cylinder 3, and printed copy sheets are discharged onto a printed copy sheet tray 31. The number of copy sheets to be printed is controlled by a counter 32.

When the copy sheet feed is completed, the member 4 is returned from its position C to its neutral position N through the positions A and B in FIG. 1. At this time, the member 4 is being moved while the member 18 is in its upper position in the member 4, thereby preventing the next succeeding master plate from being fed to the master cylinder while the preceding master plate is still on the master cylinder. While the member 4 moves from its position C to its position B, the forward end of the arm 15b of the member 15 idly moves on the arcuate edges 2lal and 22a1 of the cams 21 and 22 respectively as aforementioned without moving the member 18 to its lower position from its upper position in the member 4.

If the member 4 is moved from its neutral position N to its position D in FIG. 1 while the member 18 is in its actuated, i.e., its lower position in the member 4, then the forward end of the arm 15b of the member 35 moves while it is maintained in engagement with the right end of the mountain-shaped edge 21:12 of the automatic master plate discharge command cam 21 in FIG. 5, thereby rotating the cam 23 in a clockwise direction about the core shaft '7. A follower arm 33 is pivotally mounted on a shaft 34 secured to one of the side plates 5 and urged by a spring (not shown) to move in pivotal motion in a clockwise direction about the shaft 34 in FIG. 5. Mounted on a shaft secured to the follower arm 33 is a roller 35 which is maintained in contact with a depression of the wave-shaped cam por tion 21c of the cam 21. As the cam 21 rotates as aforementioned, the roller is brought into contact with the crest of the wave-shaped cam portion 21c of the cam 21, so that the follower arm 33 moves in pivotal motion in an anticlockwise direction about the shaft 34 (See FIG. 7).

In FIG. 5, a master plate discharged command pin 36 is secured to the forward end portion of the follower arm 33 and extends through an opening 5b formed in one of the side plates 5 and is directed toward the master plate discharge mechanism in the interior of the printing machine. When the follower arm 33 moves in pivotal motion in a clockwise direction as the member 4} is moved, the pin moves from a position shown in FIG. 5 to a position shown in FIG. 7 in the opening 517 to command a master plate discharge device (not shown) and cleaning device (not shown) to start operating.

The cam 22 is constructed such that the mountainshaped edge 22a2 has a length sufficiently great not to interfere with rotation of the cam 21 when its is moved by the member 15. The master plate feed command pin 28 and master plate discharge command pin 36 play an important role in giving instructions to start master plate feed and master plate discharge. The operation of the pins 28 and 36 is subsequently to be described.

2. Automatic Master Plate Feeding and Discharging Unit FIG. 10 shows in a side view of master plate feed and discharge unit 39 which is removably mounted on the printing machine. The unit 39 comprises a pair of side plates 40 disposed in face-to-face relationship and each formed in the upper portion with a cutout 41 which engages a shaft 42 secured to the opposite side plates 5 of the prinn'ng machine, and in the inner end of the lower portion with a cutout 43 which engages a shaft 44 secured to the opposite side plates 5 of the machine. Pivotally mounted on a shaft 45 secured to the side plates 40 is a lever 46 which pivotally supports a command member 47 through a shaft 48. The lever 46 is urged by a spring 49 to move in pivotal motion in an anticlockwise direction about the shaft 45. This pivotal movement of the lever 46 is precluded by a bend portion 46a at the free end of the lever 46 being engaged by a hook 50a of a locking member 50 which is pivotally mounted on a shaft 51 secured to the side plates 40.

Disposed below the command member 47 are a twoarm member 52 and another locking member 53 which are pivotally mounted on the shaft 51 secured to the side plates 40 as aforementioned. The locking member 53 is formed with a hook 53a upwardly and obliquely leftwardly of the shaft 51 and a bent portion 53b rightwardly of the shaft 51. The two-arm member 52 has one arm 52a which is suspended by a spring 54 from a pin 55 secured to the side plates 40 and the other arm 52b which is connected to the bent portion 53b of the locking member 53 by a spring 56.

Still referring to FIG. 10, a master plate feed lever 58 pivotally supported by a shaft 57 secured to the lower left portion of the side plates 40 is urged by the biasing force of torsion spring of high force (not shown) to move in pivotal motion in an anticlockwise direction about the shaft 57. Normally, a pin 59 attached to the forward end of the lever 58 is engaged by the hook 53 of the locking member 53 so that the lever 58 may be locked in place in its position shown in FIG. lltl. A follower 60 is disposed rightwardly of the lever 58 and pivotally supported by a shaft 6i secured to the side plates 40. The follower 60 is urged by a spring 62 to move in pivotal motion in a clockwise direction about the shaft 61, but the pivotal movement of the follower in a clockwise direction by virtue of the spring 62 is precluded by a bent portion 600 of the follower 60 abutting against a projection 58a of the lever An elongated master plate feed cam 63 extending between one of the side plates 40 and the lever 58 is pivotally supported by a shaft 64 secured to the side plates 40. A compression spring 65 is mounted between the cam 63 and shaft 61, so that the cam 63 is urged by the biasing force of the spring 65 to move in pivotal motion in a clockwise direction about the shaft 64. The cam 63 presses at its right side edge against a left and 60b of the follower 60.

A command lever 66 which is maintained in contact at its forward end portion with the master plate discharge command pin 36 is secured to a shaft 67 which pivotally supports another follower 68. The follower 68 presses against at its upper edge a projection 66a of the command lever by virtue of the biasing force of a compression spring 69 mounted between a bent portion 66b of the command lever 66 and a bent portion 680 of the follower 68. Disposed between the master plate feed lever 58 and master plate feed cam 63 is an elongated master plate discharge cam 70 which is pivotally supported by the shaft 57. Attached to the forward end of the cam 70 is a pin 71 (See FIG. 16) which normally presses against a cutout 68a of the follower 68 by virtue of the biasing force of a spring 73.

If the printing operation step switching member 4 is moved from its neutral position N to its master plate feed position A, then the roller 27 is brought into contact with the depression 220 of the master plate feed cam 22 in FIG. 8, so that the master plate feed command pin 28 moves from its phantom position 28A to its solid line position and causes the command lever 47 to move in pivotal motion in the clockwise direction about the shaft 48. During the pivotal movement of the lever 47, a pin '74 attached to the right end of the lever 47 pushes the upper side edge 62a of the two-arm member 52 (See FIG. 11) and causes the two-arm member 52 to move in pivotal motion in a clockwise direction about the shaft 5H against the biasing forces of the springs 54 and 56. As a result, the locking member 53 is charged by the spring 56. However, since the pin 59 on the lever 58 and the hook 530 of the locking member 53 presses strongly against each other while a roller 75 provided in the lever 58 is maintained in touch with a small force with a cam 76 secured to the master cylinder 2 as shown in H6. 12, the locking member 53 is prevented from moving in pivotal motion about the shaft 51. If the cam 76 rotates in an anticlockwise direction and moves from its position in FIG. to its position in FIG. 11 in which the cam 76 slightly moves by its projection 76a the roller 75, the force with which the pin 59 and hook 53a are maintained in pressing engagement with each other is reduced, thereby permitting the locking member 53 to move in pivotal motion in a clockwise direction about the shaft 511 under the influence of the spring 56. This unlocks the master plate feed lever 53.

Further anticlockwise rotation of the cam 76 brings the roller of the lever 58 into contact with the depression 76b of the cam 76 as shown in FIG. 12. This causes the lever 5% to move in pivotal motion in the anticlockwise direction about the shaft 57, so that the projection 58a of the lever 58 is released from engagement with the bent portion 60a of the follower 60 and the follower 64B is moved in pivotal motion in a clockwise direction about the shaft 61 by the biasing force of the spring 62.

During the clockwise movement of the follower 60, it moves at its left and tlb the master plate feed cam 63 to the left as shown in FIG. 12 against the biasing force of the spring 65, thereby bringing a pin 77 attached to the forward end portion of the cam 63 into engagement with an ofiset portion 790 of a locking arm 79 pivotally supported by a shaft 78 secured to the side plates 40. Thus, the master plate grip pawls provided on the master cylinder 1 are ready to be opened and closed.

During the pivotal movement of the master plate lever 58 in an anticlockwise direction, ,a pinion 81 in meshing engagement with a segmental gear mounted on the central portion of the lever 58 is caused to rotate in a clockwise direction about a shaft 82. In FIG. 13, rotation of the shaft 82 substantially integral with the pinion 81 (See FIG. 12) is transmitted to a master plate feed roller 87 through gears 83, 84 and 85 and a gear train 86. Clockwise rotation of the roller 87 about a shaft 88 supplies the uppermost copy sheet of a stack of copy sheets 90 resting on a master plate feed table 89 to pair of delivery rollers 91 and 92. Provided on the shaft 88 for rotating the feed roller 87 is a one-way clutch 93 which transmits rotation to the roller 87 when the shaft 88 rotates in a clockwise direction and does not transmit rotation to the roller 87 when the shaft 88 rotates in an anticlockwise direction upon returning of the segmental gear 80 to its original position in FIG. l2.

In FIG. 12, when the roller 75 of the master plate feed lever 58 is moved to the right by a protuberance 76c of the cam 76 and consequently the lever 58 is moved in pivotal motion about the shaft 57 against the biasing force of the torsion spring of high force (not shown), the pinion 81 is rotated in a reverse direction by the segmental gear 80.

Rotation of shaft 32 in an an anticlockwise direction in FIG. 13 causes, through the one-way clutch 93, the delivery roller 91 to rotate in an anticlockwise direction and deliver the master plate 0 to the master cylinder l. The one-way clutch 93 does not transmit to the roller 91 the rotation of shaft 82 when the latter rotates in a clockwise direction. This prevents the roller 87 and the pair of rollers 91 and 92 from rotating simultaneously. As shown in FIG. 14, pawl opening and closing means is provided on one side of the master cylinder 1. If the master cylinder 1 rotates in an anticlockwise direction, then a roller 97 mounted on a follower arm 96 pivotally supported by inner end walls la of the master cylinder 1 is pressed by a side edge 63a of the master plate feed cam 63 which is ready for operation, and the follower arm 5% moves in pivotal motion in an anticlockwise direction about the shaft 95. As shown in FIG. 15 a shaft 101 to which master plate grip pawls 98, stoppers 99 and fixture for supporting an aluminum master plate 100 are secured is rotatably supported by two inner ends 1a of the master cylinder. The shaft 101 is urged by the biasing force of a spring 102 to rotate in a clockwise direction. At the outside of the end walls of the master cylinder, an arm 103 secured to one end of the shaft 101 is formed with a bent portion 103a against which a roller 104 on the free end of the follower arm 96 is caused to press by the biasing force of a spring 105.

As the master cylinder 1 rotates in an anticlockwise direction and the roller 97 is moved to the left by the side edge 63a of the master plate feed cam 63, the follower arm 96 moves in pivotal motion in an anticlockwise direction about the shaft 95. Rotation of the follower arm 96 in the anticlockwise direction causes the arm 103 to move in an anticlockwise direction together with the shaft 101 against the biasing force of the spring 102, thereby opening the grips pawls which grip the forward end 90a of the master plate delivered by the delivery rollers 91 and 92.

Further anticlockwise rotation of the master cylinder 1 causes the roller 97 to kick a forward end 79b of the locking arm 79 (See FIG. 12). This releases the pin 77 on the master plate feed cam 63 from engagement with the offset portion 79a of the locking arm 79 and permits the cam 63 to move in pivotal motion in a clockwise direction about the shaft 64 by virtue of the biasing force of the spring 65 to be restored to its original position.

If the printing operation step switching member 4 is moved to its position B in FIG. 1 after the step of feeding a master plate to the master cylinder has been performed, the step of inking the master plate on the master cylinder will be initiated. If the member 4 is further moved to its position C, the step of feeding copy sheets between the blanket cylinder 2 and impression cylinder 3 will be initiated and duplication of the master plate will be begun. If the member 4 is moved to its position D after a predetermined number of copy sheets have been printed, the roller 35 (See FIG. 7) will be pushed out by the projection 210 of the cam plate 21, so that the master plate discharge command pin 36 moves a small distance in pivotal motion in an anticlockwise direction about the shaft 34.

As the movement of the master plate discharge command pin 36 from its dash-and-dot line position 36A to its solid line position in FIG. 16 causes the command lever 66 to move in pivotal motion in a clockwise direction about the shaft 67, the follower 68 is pulled by the spring 69 and moves in pivotal motion in the same direction as the lever 66 in slaved relationship. At this time, the pin 71 attached to the free end of the master plate discharge cam 70 is released from engagement with the cutout 68a of the follower 68 and brought into engagement with an offset portion 68b thereof. That is, the master plate discharge cam 70 rotates in an anticlockwise direction against the biasing force of the spring 73 into a position shown in FIG. 16.

As the master cylinder 1 has rotated in an anticlockwise direction and the roller 97 on the follower arm 96 is moved to rotate in an anticlockwise direction about the shaft 95 by the master plate discharge cam 70 which is standing by, the grip pawls 98 (See FIG. are opened in the same manner as in the master plate feed step to release the leading end of the master plate 0 on the master cylinder 1.

During the pivotal movement of the command lever 66 in a clockwise direction, an actuating arm 107 secured to the shaft 67 substantially integral with the lever 66 and having a screw 106 connected to its forward end portion (See FIG. 17) moves in pivotal motion in the same direction as the lever 66. This causes a master plate keep-down means 108 to move in pivotal motion about a shaft 109 from a position shown in FIG. 13 to a position shown in FIG. 17 in which a keep-down belt 110 of the means 108 presses against the outer peripheral surface of the master cylinder 1. The keepdown belt 110 is trained about a plurality of rollers l 12 and 1 13 secured to shafts 109 and 1 l 1 respectively and travels in the direction of the arrow when it is brought into pressing engagement with the master cylinder 1. The leading end portion of the master plate 0 released from the grip pawls 98 by the cooperation of the master plate discharge cam 70 with the follower arm 96 is stripped from the master cylinder 1 by stripper pawls 1 l4 and removed from the master cylinder 1 by the action of the keep-down belt 110, and discharged by a discharge roller integral with the shaft 109 and a roller 116 maintained in pressing engagement with the roller 115. This completes the master plate discharge step.

As shown in FIG. 10, a pusher 116 of the L-shape is pivotally supported by a shaft 117 secured to the forward end of the master plate feed lever 58. The L- shaped pusher 116 is urged to move in pivotal motion in a clockwise direction about the shaft 117 by a compression spring 118 mounted between a longer arm of the pusher I16 and the projection 58b of the lever 58. The clockwise pivotal movement of the pusher 116 is precluded by a bent portion 116a formed in the pusher 116 abutting against a right side edge of the master plate feed lever 58.

The pusher 116 normally rides on the bent portion 50b of the locking member 50 as shown in FIG. 10, the bent portion 1160 of the pusher 1 16 is normally spaced apart from the right side edge of the master plate feed lever 58. If the master plate feed lever moves in pivotal motion about the shaft 57, then the forward end of the pusher 116 is released from engagement with the bent portion 50b of the locking member 50 and the pusher 116 moves a small distance in pivotal motion in a clockwise direction about the shaft 1 17 by virtue of the spring 118 till the bent portion 116a thereof abuts against the right side edge of the master plate feed lever 58 as shown in FIG. 12.

When the master plate feed lever 58 moves in pivotal motion in a clockwise direction about the shaft 57 and returns to its original position, it causes the forward end of the pusher 116 to move the bent portion 50b of the locking member 50. As a result, the locking member moves in pivotal motion in a clockwise direction about the shaft 51 against the biasing force of a curved spring 1 19 mounted between the bent portion 50c of the member 50 and the pin 55, thereby releasing the free end of the etching command lever 46 locked in place by the hook 500 of the member 50.

Releasing of the etching command lever 46 from engagement with the locking member 50 simultaneously as the completion of the feeding of a master plate to the master cylinder plays an important role in the actuation of the etching solution application device presently to be described.

3. Device for Automatically Applying and Etching Solution to the Master Plate on the Master Cylinder As shown in FIG. 18, the master plate feed and discharge unit 39 comprises support arms 121) each secured to one of the opposite ends of the shaft 45 substantially integral with the etching command lever 46. The support arms 120 support bearings 121 for an etching roller subsequently to be described. An etching unit designated generally 122 in FIG. 19 and comprising various elements of the etching solution application device includes a pair of side plates 123 disposed in face-to-face relation. Each side plate 123 is formed with a cutout 124 on its right side which engages the shaft 42 secured to the side plates of the machine proper (See FIG. 1), and with a cutout 125 on its left side which engages a shaft 126 secured to the side plates 5 of the machine proper like the shaft 42, so that the unit 122 is removably mounted on the machine proper. A locking member 128 is pivotally supported by a shaft 127 secured to the upper left portions of the side plates 123, and urged to move in pivotal motion in a clockwise direction about the shaft 127 by the biasing force of a compression spring 130 mounted between a bent portion 128a of the member 128 and a pin 129 attached to the side plates 123. The locking member 128 is formed at its lower end portion with a hook 128b which is adapted to engage the shaft 126 so as to thereby secure the side plates 123 of the unit 122 to the machine proper.

An immersing roller 133 is secured to a shaft 132 journalled at opposite ends by bearings 131 each mounted on one of the side plates 123 (See 11G. 20). The immersing roller 133 has a portion which is immersed in an etching solution 135 contained in a tank 134 which is supported by a pair of supporters 137 mounted on a shaft 136 and juxtaposed to the side plates 123 as shown in FIG. 19, 20. The pair of bearings 131 each pivotally support plate 138 to which a pin 139 Y is attached. Each support plate 138 is urged to move in pivotal motion in a clockwise direction about the shaft 132 by the biasing force of a compression spring 141) mounted between a pin 139 attached to each support plate 138 and the shaft 127.

Mounted on the support plates 138 are the bearings 121 referred to hereinabove which support a shaft 142 substantially integral with an etching roller 141. As the support arms 120 pivotally move about the shaft from a dash-and-dot line position to a solid line position in FIG. 18. the bearings 121 which rest on the support arms as aforementioned moves a small distance with the support plates 138 about the shaft 132 in slaved relation so as to thereby bring the outer peripheral surface of the etching roller 141 into engagement with the outer peripheral surface of the master cylinder 1.

On the other hand, each support plate 138 is formed in its upper end portion with a bent portion 138a to which an adjusting screw 143 is connected. Each ad-- justing screw 143'abuts at its forward end against a bent portion 123a of each side plate 123. By rotating the adjusting screws 143 to adjust the distance between the screws 143 and the side plates 123, it is possible to control the force with which the etching roller 141 bears against the master cylinder 1.

Each support plate 138 is formed at its projection 1538b with a key-hole type opening 144 which loosely receives therein a bearing 1417 for supporting a shaft 146 substantially integral with a transfer roller 145. The transfer roller is urged by the biasing forces of extension springs 1 each mounted between one of the bearings 147 and a bent portion 138C of the projection 138!) of one of the support plates 138 to bear against the outer peripheral surfaces of the immersing roller 133 and etching roller 141. The transfer roller 146 functions to supply the etching solution on the immersing roller 138 to the etching roller 141. Disposed below the transfer roller 145 iswan idle roller 149 which is rotatably mounted on a shaft 150 between the support plates 1 and maintained in meshing engagement with a gear 151 secured to the etching roller 141 and a gear 152 secured to the immersing roller 133, so that rotation of theimmersing roller 133 is transmitted to the etching roller 141.

The etching roller 141 is adapted to rotate in an anticlockwise direction about a shaft 142 and its outer peripheral surface moves in a direction opposite to the direction of movement of the outerperipheral surface of the master cylinder 1 indicated by the arrow, so as to thereby enhance the effect of etching of the master plate.

The immersing roller 133 is driven by a mechanism connected to a main electric motor (not shown) of the machine proper. in FIG. 20, a follower gear 153 is secured by a screw 154 to the outer end of the immersing roller 133 and maintained in meshing engagement with a driving screw 155 disposed below the gear 153. This facilitates mounting and removal of the etching unit 122 on the machine proper. A driving shaft 157 to which the driving gear 155 is secured by a pin 156 is rotatably supported by a bearing 158 secured to right side plate 5 of the machine proper and a bearing 161 disposed below a blanket 160 secured by a screw 159 to the side plate 5. Loosely fitted over the driving shaft 157 in a position between the right side plate 5 of the machine proper and the bearing 161 is a clutch 162 which forms a pair with a clutch disc 163 secured to the shaft 157 by a pin 16 1. A chain 166 is trained about a sprocket wheel 165 substantially integral with the clutch 162 and a sprocket wheel (not shown) secured to the output shaft of the main electric motor of the printing machine, so that the torque developed by the electric motor is transmitted to the driving shaft 157 through the clutch 162 and clutch disc 163.

As aforementioned, if the printing operation step switching member 4 is moved to the master plate feed position A in FIG. 1, the master plate feed command pin 28 will be actuated and cause the master plate feed lever 58 to move in pivotal motion back and forth about the shaft 57 (FIG. 11). During the return movement of the lever 53, the pusher 116 kicks at its forward end 116b the bent portion 50b of the locking member 50 as shown in FIG. 12 and FIG. 18, thereby releasing the free end of the etching command lever 46 120 for supporting the shaft 142 of the etching roller 141 rotates in an anticlockwise direction about the shaft 132 in slaved relation to the movement of the support arms 120, thereby bringing the etching roller 141 into pressing engagement with the outer peripheral surface of the master cylinder 1 (FIG. 19). This permits the etching roller to apply an etching solution to the surface of the master plate 90 (not shown) mounted on the master cylinder 1.

It should be noted that the clutch 162 and clutch disc 163 shown in FIG. engage each other to cause the immersing roller 133 and etching roller 1 11 to rotate only when the member 4 is moved to the master plate feed position A in FIG. 1, and that the clutch is disengaged and the aforementioned rollers stop rotating when the member 4 is moved to any other position than the position A. Description of means for causing engagement and disengagement of the clutch 162 and clutch plate 163 will be omitted.

The etching step is terminated when the member 4 is moved from the master plate feed position A. If the member 4 is moved to the inking position, then the master plate feed command pin 28 moves to the phantom position 28A in FIG. 11 and causes the bent portion 46b of the etching command lever 46 to move in a clockwise direction about the shaft 45 (FIG. 18). As a result, the lever 46 is returned from its position in FIG. 18 to its position in FIG. 10. This results in the bearings 121 of the etching roller 141 being returned to the phantom positions shown in FIG. 18 by the support arms 120. Thus, the etching roller 141 is released from pressing engagement with the master cylinder 1. When the etching command lever 46 has returned to its original position, the bent portion 460 at the forward end of the lever 46. is engaged by the hook 50a of the locking member 50 under the influence of the spring 1 19, so that the etching command lever 46 is locked in its original position.

4. Preliminary Etching Roller Wetting Device Application of an etching solution to a master plate is automatically started as the instructions are given to the etching solution application device simultaneously as the master plate is mounted on the master cylinder. Heretofore, it has been impossible to perform an etching solution application operation satisfactorily when the instructions are given to the etching solution application device and the etching roller is rapidly brought into pressing contact with the master plate on the master cylinder because the former is not sufficiently wet to do the task. The prior art etching solution application device has had a disadvantage in that a certain period of time has to elapse before a sufficiently large amount of etching solution is supplied from the immersing roller in the etching solution tank to the etching roller. Another disadvantage has been that rubbing of the surface of the master plate by a dried etching roller cause damage to the master plate. These disadvantages can be obviated by supplying a substantial amount of etching solution to the etching roller beforehand prior to actuation of the etching solution application device.

In FIG. 1 and FIG. 2, a plate having an arm 167 is secured to the tubular shaft 6. Pivotally supported by a shaft 169 secured to the forward end of the plate which has the arm 167 is the right end of a connecting rod 168 which has a left end pivotally supported by a shaft 172 secured to the free end of a crank arm 171 substantially integral with a shaft which is supported at opposite ends by the left and right side plates 5 of the printing machine. The shaft 170 extends outwardly through the right side plate 5 (See FIG. 20) and carries at its end a earn 173 as shown in FIG. 21. Thus, the cam 173 is connected to the printing operation step switching member 4 through the arm 167, connecting rod 168 and crank arm 71, and moves in the same direction as the member 4 when the latter is moved from its neutral position N to its positions A, B, C and D. In FIG. 21, a follower lever 174 is disposed tothe right and in the vicinity of the earn 173. The lever 174 is pivotally supported by a shaft 175 secured to the right side plate 5 of the machine, and urged to move in pivotal motion in an anticlockwise direction about the shaft 175 by the biasing force of a compression spring 177 mounted between a bent portion 174a on the right end of the lever 174i and a pin 176 attached to the right side plate 5. This anticlockwise movement of the lever 174 brings a roller 179 pivotally supported by a shaft 178 secured to the lefi end of the lever 174 into pressing engagement with a major diameter portion 173a of the cam 173. Maintained in contact with a minor diameter portion 1173b of the cam 173 is a roller 181 of a switch 180 which is adapted to actuate the main switch of the printing machine as the roller 181 rides on two major diameter portions 173a and 173d of the cam 173 upon movement of the member 4 to any of the positions other than the neutral position.

Attached to the clutch disc 163 is a pin 182 which is adapted to rotate about the shaft 157 only when the roller 179 of the follower lever 174 rides on the major diameter portion 1734 of the cam 173 as shown in FIG. 21. If the roller 17? is brought into contact with a minor diameter portion 1732 of the cam 173 and the follower lever 174 moves in pivotal motion a small distance about the shaft 175 as shown in FIG. 22, then the pin 182 abuts against an offset portion 174a of the lever 174 and stops it from rotating.

As aforementioned, the cam 173 rotates in conjunction with the movement of the member 4. It is when the member 4 is moved to the inking position B or the copy sheet feed position C shown in FIG. 1 that the roller 179 of the lever 17d is brought into contact with the minor diameter portion 173e of the cam 173 as shown in FIG. 22. When the member 4 is disposed in the master plate feed position A or master plate discharge position D, the roller 179 is in contact with the major diameter portion 173a of the cam 173. Accordingly, movement of the member 4 to the master plate feed position A or master plate discharge position D causes the rollers 133, 145 and 141 of the etching unit 122 (See FIG. 19) to rotate; movement of the member 4 to the inking position B or copy sheet feed position C does not cause the rollers 135, 145 and 141 to rotate.

If the member 4 is moved to the master plate feed position A while the switching actuating member 18 is in its lower position within the member 4 in FIG. 1, then the master plate feed cam plate 22 rotates in an anticlockwise direction about the shaft 7 (See FIG. 2) and gives instructions to the master plate feed and discharge device 39 to start feeding a master plate as aforementioned. Upon completion of feeding of the master plate to the master cylinder 1, instructions are given to the etching command lever 46 substantially integral with the shaft (FllG. 18) to start applying an etching solution, whereby the shaft 45 is rotated a small angular distance in an anticlockwise direction. As a result, the support arms 12% secured to the shaft 45 move from the dash-and-dot line position to the solid line position in FIG. 18, so that the bearings 121 for the etching roller resting on the support arms H rotate in an anticlockwise direction about the shaft 132. This brings the etching roller 141 into pressing engagement with the master plate ti on the master cylinder ll.

On the other hand, when the member 4- is moved to the master plate feed position A, the crank arm ll'll is moved in pivotal motion in an anticlockwise direction through the arm 167 secured to the tubular shaft 6 and the connecting rod. This causes the cam 173 substantially integral with the crank arm 171 to rotate a small angular distance in an anticlockwise direction from its position in FIG. 21. Anticlockwise rotation of the cam 173 causes the roller 181 of the switch 180 to ride on the major diameter portion 1730 of the cam 1173, so that the main switch of the printing machine is actuated and the clutch 162 shown in FIG. 20 is rotated. During the rotation of the cam 173 caused by the movement of the member 4 to the master plate feed position A, the roller 179 of the follower lever l7 i remains in contact with the major diameter portion 173a of the cam 1'73 and consequently the follower lever i174 remains in its position in FIG. 21. Therefore, the clutch disc 163 rotates with the clutch 152 as the switch 180 is actuated because the offset portion 174a of the lever 174 is not in the path of rotation of the pin 182 attached to the clutch disc 163. Thus, the rotation transmitted to the clutch 162 is transmitted to the shaft 157 and rotates the rollers 133, 145 and 3141 on the support plates 138 (See FIG. 19).

To sum up, the rollers of the etching unit are rotated beforehand while a master plate is being fed to the master cylinder upon movement of the member 4 to the master plate feed position A, so that the etching solution application roller can be wetted with an etching solution. Upon completion of the mounting of the master plate on the master cylinder, the etching solution application roller is actuated to start applying the etching solution to the master plate on the master cylinder. When a series of master plates are duplicated successively, the preliminary etching solution application roller wetting step can be carried out in the same manner if the member 4 is moved to the master plate discharge position D after completion of duplication of one master plate. This ensures that an etching solution application operation is performed satisfactorily upon completion of mounting of the next successive master plate on the master cylinder.

5. Device for Terminating the Rotation of the Etching Solution Application Roller The etching solution application step is carried out as soon as a master plate is mounted on the master cylinder. in the etching solution application step, the transfer roller is brought into pressing engagement with the immersing roller immersed in the etching solution in the etching solution tank and the etching solution application roller to supply the etching solution to the etching solution application roller which is caused to press against the master plate on the master cylinder to apply the etching solution to the master plate. If the aforementioned rollers are permitted to rotate idly while the etching solution application step is not performed or when the etching solution application roller is not maintained in pressing contact with the master cylinder, the etching solution supplied from the tank will be collected on the outer peripheral surface of the etching solution application roller. If the amount of the solution collected is too great, the solution may be scattered and spoil the master plate. Thus, it is necessary to cause the etching solution-application roller to remain stationary when other steps than the etching solution application step or the hiking and copy sheet feed steps are performed.

Movement of the member 4 from the master plate feed position A to the inking position B causes the cam 173 connected to the member 4 to rotate in an anticlockwise direction from its neutral position in FIG. 21, bringing the roller 179 into contact with the minor diameter portion ll73e of the cam 173. If the roller 179 is brought into engagement with the minor diameter portion ll73e as shown in MG. 22, then the follower lever i174 moves small distance in pivotal motion in an anticlockwise direction about the shaft and causes the offset portion 174a to be disposed in the path of movement of the pin H82 attached to the clutch disc 163 so that the offset portion 174a may engage the pin 182. This causes the clutch disc 163 to stop rotating, so that the immersing roller 133 (See FIG. 20) driven by the shaft 157 substantially integral with the clutch disc 163 also stops rotating and the supply of the etching solution to the etching solution application roller is shut off.

6. Device for inking the Master Plate Upon completion of the etching solution application step, inking of the master plate is initiated.

in FIG. 23, an oscillator roller 1183 supported by a shaft 1 secured to the machine proper in suitable positions is disposed upwardly and obliquely leftwardly of the master cylinder ll. A pair of support members 135 and 1186 are oscillatably supported by the shaft 184. Loosely received in an opening 187 of the keyhole type formed in the forward end portion a of an arm of the support member 185 extending above the master cylinder l is a bearing 1188 which supports a shaft of an inking roller ass. The bearing 188 is urged to move toward the oscillator roller 183 by the biasing force of an extension coil spring 250 mounted between a bent portion lbfid formed at the forward end of the support member 185 and the bearing 188. This movement of the bearing 188 is precluded by an arm 192 which is secured to the forward end of a bent arm mob of the support member M36 and formed with an offset portion E9212 in the lower end of one side edge thereof. With the bearing 13% pressing against a side edge of the arm H92, the inking roller i8? is spaced apart a small distance from the oscillator roller H83.

An inking roller H93 forming a pair with the inking roller 189 is journalled by hearing means identical with that of the inking roller 189 and disposed in a forward end portion in of a downwardly extending arm of the support member 196. A bearing received in a bearing operating 1% is urged to move toward the oscillator roller 1&3 by the biasing force of a coil spring ll. This movement of the bearing 195 is precluded by the lower end edge of an arm 185b of the support member 185. With the bearing 195 pressing against the lower end edge of the arm 185b, the inking roller 193 is spaced apart a small distance from the oscillator roller 185. The arm 185b is formed with an offset portion at the end of one side edge thereof.

A compressive spring 199 of relatively great force is mounted between a pin 197 attached to the upper end of one support member 185 and a pin 198 attached to the bent arm 1861) of the other support member 186. The biasing force of the spring 199 urges one support member 185 to move in pivotal motion in a clockwise direction about the shaft 184 and the other support member 186 to move in pivotal motion in an anticlockwise direction about the shaft 184. The pivotal movement of one support member 185 caused by the spring 199 is restricted by the engagement of a roller 200 supported by the support member 185 with a rotary cam 201, and the pivotal movement of the other support member 186 caused by the spring 199 is restricted by the engagement of a roller 202 supported by the support member 189 with the rotary cam 201. With the rollers 200 and 202 pressing against major diameter portion 201a of the rotary earn 201 as shown in FIG. 23, the two inking rollers 189 and 193 are spaced apart a small distance from the master cylinder 1.

The rotary cam 201 is mounted on the aforementioned shaft 170 and adapted to rotate through a predetermined angle in conjunction with the move ment of the member 4. The various elements shown in FIG. 23 are disposed in positions which they assume when the member 4 is in its neutral position.

A fountain roller 203 disposed leftwardly of the inkin g roller 193 is supported on a shaft 204 rotatably supported by the machine proper which loosely supports an oscillator member 205. The oscillator member 205 has a rightwardly and obliquely upwardly extending arm which is formed with a cutout 206 which loosely receives therein a bearing 209 supporting a shaft 208 of a ductor roller 207 pressing against the fountain roller 203.

The oscillator member 205 is urged to move in pivotal motion in a clockwise direction about the shaft 204 by the biasing force of a spring 211 mounted between a pin 210 attached to an immovable member (not shown) and a leftwardly extending arm of the member 205. This movement of the member 205 is restricted by the engagement a projection 205 thereof with a projection 186d of the support member 186.

Movement of the member 4 from its neutral position to its master plate feed position A causes the rotary cam 201 to move through a predetermined angle in an anticlockwise direction, thereby bringing the rollers 200 and 202 of the two support members 185 and 186 respectively into engagement with minor diameter portions 201b of the cam 201. This causes the support member 185 and the support member 186 to move in pivotal motion in a clockwise direction and an anticlockwise direction respectively about the shaft 184. Pivotal movements of the support arms 185 and 186 brings the bearing 188 of one inking roller 189 into engagement with the offset portion 1920 of the arm 192 and the bearing 195 of the other inking roller 193 into engagement with the offset portion c of the arm 185!) of the member 135. This results in the two inking rollers 189 and 193 pressing against the oscillator roller 183, so that the ink is formed by these three rollers 183, 189 and 193. With the two rollers 200 and 202 being maintained in engagement with the small diameter portions 2111b of the rotary cam 201, the two inking rollers 189 and 193 are prevented from pressing against the master cylinder 1.

The master plate 0 on the master cylinder 1 which has been inked as aforementioned is caused or press against the blanket cylinder 2 (See FIG. 1) to transfer the inked image of the master plate to the blanket cylinder 2 which is maintained in contact with the impression cylinder 3, so that the inked image of the master plate is transferred to copy sheets fed between the blanket and impression cylinders successively. This printing step is carried out by known process, its description herein being omitted.

7. Blanket Cylinder Cleaning Device Upon completion of printing of a predetermined number of copy sheets, the master plate on the master cylinder is removed and discharged, and the inked image left on the blanket cylinder is removed by cleaning the outer peripheral surface of the blanket cylinder. This completes the duplication of one master plate.

in FIG. 24, a follower lever 212 is pivotally supported by a shaft 213 secured to side plates (not shown) so that the lever 212 may be disposed leftwardly of the cam 1'73 previously described. The lever 212 is urged to move in pivotal motion in a clockwise direction about the shaft 213 by the biasing force of a compression spring 214 connected at one end to one of the side plates 5 of the machine and at the other end to the lever 212. Supported by a shaft 215 secured to right end portion of the lever 212 is a roller 216 which is urged by the biasing force of the spring 214 to press against the major diameter portion 173a of the cam 173. Supported by a shaft 217 secured to the left end portion of the lever 212 is a roller 218 against which presses a bent portion 220a of an actuation lever 220 pivotally supported by a shaft 219 secured to the side plates (not shown) and urged to move in pivotal motion in an anticlockwise direction.

Disposed to the left and in the vicinity of the blanket cylinder 2 is a cleaning unit generally designated 221 which is removably mounted onthe printing machine by fitting pins 223 attached to the lower portions of two side plates 222 of the unit 221 in openings (not shown) formed in the left and right side plates 5 of the printing machine. The cleaning pins 223 can be removed from the openings in the right and left side plates of the machine by moving a knob 224 inwardly of the unit 221, thereby permitting to removably mount the unit 221 on the printing machine.

The cleaning unit 221 is urged to move in pivotal motion in a clockwise direction about the pins 223 by the biasing force of a compression spring 225 connected at one end to one of the side plates 5 of the machine and at the other end to a projection 222a of one of the side plates 222. This clockwise movement of the cleaning unit 221 is restricted by the engagement of a pin 226 attached to the inner side of one of the side plates 222 with a lower bent portion 220b of the actuation lever 220. Thus, the unit 221 is normally held in the position shown in H6. 24. 

1. An offset printing machine having a rotatable master cylinder adapted to hold master plates fed thereto, and an actuation member movable from a neutral position to a first position to activate a master plate feeding unit for starting and completing the feeding of a master plate from a master plate feed tray to the master cylinder to be held thereby, wherein the improvement is in a master plate etching unit comprising: an etching roller and means for mounting said etching roller for movement from a neutral position in which it does not contact the master cylinder to an etching position in which it is in pressing engagement with the master cylinder to etch a master plate held thereby; means actuable for applying etching solution to the etching roller; means responsive to the actuation of the master plate feeding unit by moving the actuation member from its neutral to its first position for actuating the means for applying etching solution to the etching roller, while the etching roller is in its neutral position, said actuating means including arm means drivingly connected with the actuation member to move therewith from a neutral to a first position, a cam drivingly connected with the arm means to move therewith in rotational motion from a neutral to a first position, a switch drivingly connected with the cam to be activated thereby when the cam moves to its first position, and a clutch connected with the switch and activated thereby upon the actuation of the switch, said clutch being drivingly connected with the means for applying etching solution to the etching roller to actuate the last recited means upon actuation of the clutch by the switch; means responsive to completion of the feeding of a master plate to the master cylinder for moving the etching roller from its neutral to its etching position, said means for moving the etching roller from its neutral to its etching position including a master plate feed lever drivingly connected with the master plate feeding unit to move from a neutral to a master plate feeding position upon initiation of a master plate feeding operation and to move thereafter from the master plate feeding position back to the neutral position, an etching command lever drivingly connected with the master plate feed lever and responsive to its moving back to the neutral position to move from a neutral to an etching position, support arms drivingly connected with the etching command lever and with the etching roller to move the etching roller from its neutral to its etching position in response to the moving of the etching command lever from its neutral to its etching position; and whereby the etching roller is prewetted with etching solution prior to its being brought in contact with a master plate held onto the master cylinder.
 2. An offset printing machine as in claim 1 wherein the actuation member is movable from its first position to a second position for carrying out a different printing step and including means drivingly connected with the actuation member for moving the etching roller from its operative to its neutral position when the actuation member is moved from its first to its second position.
 3. An offset printing machine as in claim 2 including means drivingly connected to the actuation member and responsive to its moving from the first to the second position to de-actuate the means for applying etching solution to the etching roller.
 4. An offset printing machine as in claim 1 wherein the means actuable for applying etching solution to the etching roller comprise a reservoir for etching solution, an immersion roller at leaSt partly immersed in the etching solution in said reservoir, an idle roller in driving engagement with the immersion roller and with the etching roller to effect concurrent rotation thereof, and a transfer roller in pressing engagement with both the immersion roller and the etching roller to transfer etching solution from the immersion roller to the etching roller when the immersion and etching rollers are rotating.
 5. An offset printing machine as in claim 4 wherein the actuation member is movable from its first position to a second position for carrying out a different printing step and including means drivingly connected to the actuation member and responsive to its moving from the first to its second position to deactuate the means for applying etching solution to the etching roller, said deactuating means comprising a cam drivingly connected with the actuation member and responsive to its moving from its neutral to its first position to move from a neutral to a first position, a cam follower engaging the cam to move therewith from a neutral to a first position, and means drivingly connected with said cam follower and responsive to its moving to its second position to inhibit rotation of the immersion roller.
 6. An offset printing machine as in claim 1 wherein the actuation member is movable from its first position to a second position for carrying out a different printing step, and is movable from its second position to a third position, and including inking means drivingly connected with the actuation member and responsive to moving the actuation member to its third position to ink a master plate mounted on the master cylinder.
 7. An offset printing machine as in claim 6 wherein the actuation member is movable from its third position to a fourth position, and including a blanket cylinder, blanket cylinder cleaning unit having a first position out of contact with the blanket cylinder and a second position in pressing engagement with the blanket cylinder, means normally biasing the cleaning unit in its first position, means drivingly connected with the actuation member and responsive to its moving to its fourth position to move the blanket cylinder cleaning unit into its second position in pressing engagement with the blanket cylinder.
 8. An offset printing machine as in claim 7 wherein the means for moving the blanket cylinder cleaning unit to its second position comprise a cam drivingly connected with the actuation member and responsive to its moving to its fourth position to move from a neutral position to an operative position, a cam follower engaging the cam and moving from a neutral to an operative position when the cam moves to its operative position, and means drivingly connected with the cam follower and responsive to its moving to its second position to move the blanket cylinder cleaning unit in pressing engagement with the mass blanket cylinder against the force of the biasing means. 